1. Field of the Invention
The present invention relates to a device for breaking the circumferential bead of a pneumatic tire. More particularly, the present invention relates to a bead breaking device for use on the oversized tires on the rear wheel of an agricultural tractor.
2. Prior Art
Agricultural tractors and the like are usually equipped with two very large tires on their rear wheel. A great deal of force must be applied to remove the large tractor tire from its rim. Generally, this operation is accomplished by the use of a hammer and mallet or by the use of relatively large specialized devices which often require the dismounting of tire and wheel rim from the tractor.
A preliminary search was conducted on the above, and the following prior art U.S. patents were uncovered:
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 2,122,388 Wilkerson June 28, 1938 2,606,602 Manupello May 25, 1950 2,520,330 Northrup et al. August 29, 1950 2,581,086 Edenfield et al. January 1, 1952 2,801,684 Salsbury September 2, 1954 2,775,290 Monclaro March 1, 1955 2,753,923 Bowyer July 10, 1956 3,537,501 Johnson November 3, 1970 3,574,318 Gerbeth et al. April 13, 1971 3,847,197 Konen November, 12, 1974 3,880,220 Bunts April 29, 1975 4,256,161 Chisum March 17, 1981 ______________________________________
A tire bead forcing device is disclosed in U.S. Pat. No. 2,581,086 to Edenfield and includes a manually operated hydraulic pump. The tire is forced away from the wheel rim by means of a presser foot and the machine is fastened to the rim by a spring-loaded vise-like member. This device has an essentially canister type of hydraulic pump with the actuating means of the pump located on its rear end.
Another tire loosening tool having a large canister type pump is disclosed in U.S. Pat. No. 2,520,330 to Northrup et al. The clamping means of this invention comprises a lever style device with a handle which pivots a resilient pad which engages the wheel rim.
In U.S. Pat. No. 3,847,197 to Konen, a tire bead demounting apparatus having a relatively large jaw assembly is disclosed. This invention also includes a large arcuate yoke and requires an auxiliary source of pressure to power the plunger member in order to break the tire bead.
No prior art device discloses a compact device that does not require an auxiliary source of pressure. No self-contained prior art device disclosed is capable of being used in the confined space of the inner wall of the tire.